The present invention relates generally to light projection systems and more particularly to light valve projection systems.
Conventional scanning and display devices have suffered from time bandwidth limitations since they have generally relied upon standard television systems utilizing conventional vidicon tube scanners and CRT monitors. The frequency response of these conventional television systems does not provide the resolution necessary for optical surveillance systems especially when coupled to a projection which produces a magnified image.
As a result of these limitations, photodetector scanning arrays have been utilized in conjunction with light emitting diodes which each have a time bandwidth response of approximately 1 to 2 megahertz. Since each element of the array increases the bandwidth, a typical array of 100 elements provides a bandwidth of 100 to 200 megahertz which is sufficient information for a detailed image on even a large screen.
However, it has been found that an LED output array does not produce sufficient light to project a bright picture without further amplification. Although light valves have been used to amplify light, they are generally used used in conjunction with conventional television systems rather than LED's since the output of the LED's is insufficient to activate the light valve. Therefore, the prior art systems leave the choice between a photodetector scanning array in conjunction with LEDs which gives a projected picture with good clarity and resolution but insufficient brightness, or a conventional scanning and display device which produces a picture that is sufficiently bright but lacks clarity and resolution.